Polyimide is used as one of insulating materials in a semiconductor device. Polyimide is used for an interlayer dielectric film, a passivation film or the like as polyimide has high adhesive properties and can lower a leak current. Such polyimide is especially considered to be favorable as an insulating film in a three-dimensional packaging where a semiconductor chip is stacked in order to increase integration degree of a semiconductor device.
As one of methods of forming such a polyimide film, Vapor Deposition Polymerization (Vapor Deposition Copolymerization) in which Pyromellitic dianhydride (PMDA) and 4,4′-Oxydianiline (ODA) are used as source monomers is known.
In the Vapor Deposition Polymerization, PMDA and ODA, which are low molecular monomers with high reactivity, are co-vaporized on a surface of a substrate provided in a chamber and copolymerized on the surface of the substrate to obtain polyimide, which is giant molecule polymer.
Specifically, the Vapor Deposition
Polymerization is as follows.PMDA+ODA→polyamic acid (PAA)→polyimide (PI)+H2O
In a substrate processing apparatus which performs film deposition by the Vapor Deposition Polymerization, source monomers which do not contribute to the Vapor Deposition Polymerization on the substrate are exhausted in a form of monomers without contributing to the film deposition of a polyimide film to reach inside a vacuum pump which evacuates a chamber of the substrate processing apparatus. It is known that temperatures of such source monomers are lowered until the source monomers reach the vacuum pump so that the source monomers are changed from gasses to a state of solid or the like and fixed or the like in the vacuum pump to cause a trouble of the vacuum pump. Thus, it is necessary to remove these source monomers before these source monomers reach inside the vacuum pump. As such an apparatus, a vacuum polymerization apparatus which includes a monomer trap including a water cooling coil is disclosed (Patent Document 1, for example).
Further, in a general vacuum film deposition apparatus where vaporized materials of polymer are not used as source materials, a removing apparatus is provided between a chamber and a vacuum pump in order to prevent evacuated unreacted components from introducing into the vacuum pump as contaminants. As one kind of such removing apparatuses, a removing apparatus in which unreacted components are reacted in the removing apparatus to be adhered on an inside wall so that the unreacted components are removed is disclosed (Patent Document 2, for example).
On the other hand, a substrate processing apparatus having a function to capture a gas component using a trap where one end of the trap is connected to an end of an expansion pipe, and is capable of changing over between a capturing mode and a non-capturing mode by extending and shrinking the expansion pipe is disclosed (Patent Document 3, for example).